Section 03-06: Starting System
1994 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Pinpoint Tests

  

PINPOINT TEST A: ENGINE CRANKS SLOWLY

 

A1 CHECK FOR VOLTAGE TO STARTER

NOTE: Hoist vehicle (if necessary) to access starter solenoid terminals.

 CAUTION: Remove plastic safety cap on starter solenoid and disconnect hardshell connector at starter solenoid "S" terminal as described under Removal and Installation in this Section.

Yes
GO to A2.

No
CHECK wire connections between battery and starter solenoid . CHECK ground connections at battery to ground and starter solenoid to ground for an open, short or security. If secure, REFER to Section 14-00 and check battery charging system.

 

A2 MANUALLY CRANK STARTER

Yes
GO to A3.

No
REPLACE starter motor . REFER toRemoval and Installation procedures in this Section. RETEST new starter motor .

 

A3 CHECK CIRCUITRY TO STARTER

  • Check Circuit 37 (Y) for open between ignition fuse and starter motor . Check ISO-starter relay. Check for short to ground.
  • Check Circuit 33 (W/PK) and 32 (R/LB) for open between ignition switch and starter motor . Check for short(s) to ground.
  • Does the circuitry from starter motor retain continuity and have no shorts to ground?
Yes
REFER to Section 14-00 to check ignition switch for shorts. CHECK ignition fuse for short to ground.

No
REPLACE ISO-relay as required. SERVICE or REPLACE circuit(s) that are open or shorted as required.

  

PINPOINT TEST B: ENGINE DOES NOT CRANK

 

B1 CHECK FOR VOLTAGE TO STARTER

NOTE: Hoist vehicle (if necessary) to access starter solenoid terminals.

 CAUTION: Remove plastic safety cap on starter solenoid and disconnect hardshell connector at solenoid "S" terminal as described under Removal and Installation in this Section.

  • Ignition switch OFF. Transmission in PARK or NEUTRAL.
  • Using Digital Volt-Ohmmeter 007-00001 or equivalent, check for voltage from starter "B+" terminal to starter drive end housing (ground).
  • Does voltmeter indicate 12 to 12.45 volts DC?
Yes
GO to B2.

No
CHECK wire connections between battery and starter solenoid . CHECK ground connections at battery to ground and starter solenoid to ground for an open, short or security. If secure, REFER to Section 14-00 and check battery charging system.

 

B2 MANUALLY CRANK STARTER

  • Ignition switch OFF. Transmission in PARK or NEUTRAL.
  • Connect one end of a jumper wire to the starter "B+" terminal and momentarily touch the other end to solenoid "S" terminal.
  • Does starter motor crank and crank quickly?
Yes
GO to B3.

No
REPLACE starter motor . REFER to Removal and Installation procedures in this Section. RETEST new starter motor .

 

B3 CHECK CIRCUITRY TO STARTER

  • Check Circuit 37 (Y) for open between ignition fuse and starter motor . Check ISO-starter relay. Check for short to ground.
  • Check Circuit 33 (W/PK) and 32 (R/LB) for open between ignition switch and starter motor . Check for short(s) to ground.
  • Does the circuitry from starter motor retain continuity and have no shorts to ground?
Yes
GO to B4.

No
REPLACE ISO- relay as required. SERVICE or REPLACE circuit(s) that are open or shorted as required.

 

B4 CHECK IGNITION FUSE

  • Check ignition fuse in the engine compartment fuse box.
  • Is ignition fuse open?
Yes
GO to B5.

No
GO to B6.

 

B5 CHECK FOR GROUNDED POWER FEED

  • Check Circuit 37 (Y) from the ignition fuse socket to ground.
  • Does continuity exist?
Yes
SERVICE or REPLACE short to ground. REPLACE ignition fuse and RETEST starter system.

No
REPLACE ignition fuse and RETEST starter system.

 

B6 CHECK FOR IGNITION SWITCH FEED

  • Check voltage to the ignition switch .
  • Does voltmeter indicate 10-12 volts DC?
Yes
GO to B7.

No
SERVICE or REPLACE open or shorted circuit as required. RETEST starter system.

 

B7 CHECK IGNITION SWITCH FOR OPEN

  • Reinstall starter system.
  • With ignition switch in the START position, check voltage from the "ST" terminal on the ignition switch to ground.
  • Does voltmeter indicate 10 to 12 volts DC?
Yes
CHECK fuel system. REFER to Section 10-00. CHECK engine system. REFER to Section 03-00

No
Ignition switch is open. REPLACE as required. RETEST starter system.

  

PINPOINT TEST C: UNUSUAL STARTER NOISE

 

C1 CHECK STARTER MOUNTING

  • Check starter motor mounting to be flushed- not cocked. Check all connections to be secure. Refer to Removal and Installation for mounting information.
  • Check other necessary components related to the starting system to be securely mounted. Ignition switch , regulator/ distributor , battery and transmission switches.
  • Check wiring connections for damage or shorting due to corrosion or stray wires.
  • Are the starting system components and wiring secure and undamaged?
Yes
GO to C2.

No
SERVICE or REPLACE wiring or component mountings as required.
RETEST starting system for noises.

 

C2 CRANK ENGINE

  • Put ignition switch in START then RUN position. As engine is "starting," listen to individual components for noise due to gear tooth damage, shorting, sparking, or knocking.
  • Pinpoint noise to component.
  • Is noise due to ring gear tooth damage?
Yes
REPLACE starter solenoid .

No
If noise is shorting or sparking, check grounded feeds to battery or starter motor .
REFER to Section 14-00.
If noise is knocking, REFER to Section 03-00 for engine inoperation diagnosis.